1. Field of the Invention
The present invention relates to preparation of photographic media, such as slides and foils, as are used for business meetings and other purposes. More particularly, the present invention relates to an apparatus for preparing color slides and other photographic media containing textual material and x-y addressable graphics for a variety of uses.
2. Background of the Invention
Photographic reproduction of alpha-numeric characters is known and currently in use, particularly in the fields of phototypesetting and microfilm technology. As used herein the term "alpha-numeric characters" includes logos and icons. Systems are known which transfer images of alpha-numeric characters from a cathode ray tube (hereinafter "CRT") to photographic media. Such systems are primarily used in the field of phototypesetting. These systems can be broken down into two categories: those with less than 1200 lines of resolution across a slide (low-medium resolution) and those with 2000 or more lines of resolution across a slide (high resolution). Typically, film resolution is limited at about 4000 lines of resolution across a 35 mm slide. One major drawback of low-medium resolution systems is that the resolution of the images produced on the film is limited by the raster scan resolution capability of the CRT used to generate the character image. Such systems perform adequately the task of conveying information, but they cannot meet the demand for high resolution text and graphics usable for creating high quality slides and photographic media suitable for presentations at business meetings and other similar applications.
Other problems inherent in low resolution, low cost systems which make use of CRT's in generating images to be projected onto photographic media include distortion, soft focus, exposure variations at edges and color impurity. Distortion of images is caused by the fact that the CRT is not flat but is curved and thus images generated on a CRT are likewise slightly curved making the generation of straight lines in all areas of the CRT next to impossible. Soft focus can occur in portions of CRT generated images because the spot size of the electron beam is larger at the edges than in the center of the CRT. Exposure variations at edges occur because the intensity of the projected image from the CRT can vary significantly from center to edge because the distance from the electron gun to the corner of the CRT is greater than the distance from the electron gun to the center of the CRT. Color impurity is caused by the use of additive color systems employing three filters as are in effect used in CRT's. Such systems can induce color fringing and edge effects due to variations in image size over time with exposures from each of the three filters.
Systems for generating high quality graphics are known, but such systems are generally complex and expensive, and generate graphic images on CRT screens or on X-Y plotters using a moving stylus. For example, there are very high resolution CRT based devices available that are designed to image directly onto slide film. Typically 2000 to 4000 raster scan lines across the CRT are required in order to generate these high resolution images. CRT's with such high resolution are very expensive and systems employing them for the generation of high resolution images on film require a large amount of sophisticated and expensive electronics in order to translate the graphic information from the host computer to images on film. The inventors are unaware of non-CRT based apparatus which is capable of generating both high resolution alpha-numeric characters and graphics for printing on colored photographic media such as 35 mm slides, or larger transparent foils.
The use of high-resolution optical transparencies containing type font shapes is known for applications such as phototypesetting. The use of high-resolution optical transparencies as the source for alpha-numeric images eliminates the need for a high-resolution CRT and for the electronic control circuitry necessary in order to make use of such a high-resolution CRT. A high-resolution optical transparency is stored on a photographic or other similar media. By projecting a light from the back of the high-resolution optical transparency, a high-resolution image of the desired character, icon, logo or other image can be readily obtained, focused, and projected onto the photographic media.